Satisfying the world’s ever-increasing demand for secure, affordable electricity while maintaining a low carbon footprint is one of the greatest challenges of this century. Bringing together nuclear fission with “low carbon” technologies can enable this much-needed “green energy” transition in an optimized way.
Public perception and government support of nuclear deployment are rapidly changing in a positive way due to the pressing challenges of climate change and energy independence and security. Each country can choose its own energy mix, but it is important to consider all technologies available today.
Often, an argument against implementing nuclear power as a source of secure, affordable, low-carbon energy is related to the “problem” of how and where to store nuclear waste. It should be noted that even in countries where nuclear power is not adopted for energy/electricity production, nuclear storage facilities and repositories are needed to safely store radioactive waste, whether from the nuclear sector or from the use of radioactive materials in the medical, research and industrial sectors.
The implementation of nuclear as an energy source adds on the need to propose a long term strategy for the management of nuclear waste. Spent nuclear fuels (SNF) and certain re-processed, high-level waste (HLW) resulting from the operation of nuclear power plants specifically require treatment and plans for long term management and disposal. Many countries have faced difficulties and controversy regarding their long-term management strategies.
Managing Nuclear Waste
Each choice and long-term strategy for managing SNF and HLW is based on a country’s future energy needs and the waste type, volume, and radiological characteristics. There are currently two options that countries can safely and securely utilize in accordance with international treaties and rules. Both of them are to be considered and can be implemented in parallel. Regarding the implementation of repositories for SNFs there is nowadays a generally new imperative for countries to propose and develop a unified credible strategy to safely and permanently manage SNFs.
Option 1 – SNF as waste
For over 60 years, countries have faced challenges in deciding how to permanently manage and store HLW and SNF. A permanent solution being considered for the long-term containment and isolation of HLW and SNF involves using deep geological repositories. Finland and Sweden have specifically adopted and developed the option of deep geological repositories based on the mined repository concept and are proceeding with their plans. Other deep geological options and technologies are also being considered, including the use of deep boreholes instead of mined repositories.
Deep geological repositories are designed and built to enable the isolation and containment of HLW and SNF through a combination of engineered and natural barriers, known as the multi-barrier engineering approach. The synergistic exploitation of several redundant engineered/natural barriers ensures the protection of the environment from SNF’s inadvertent release and potential transport. At the same time, it minimizes the interaction between the environment and SNFs for several thousands of years.
Option 2 - SNF as an asset and available for reprocessing
Most nuclear power plants in the world nowadays are “thermal" reactors, where a so-called "fissile" fuel is exploited thanks to the presence of abundant "slow/thermal" neutrons. A fissile material is a material that can fission when capturing slow neutrons, resulting in a reaction that generates more neutrons for other nuclear reactions and thermal/kinetics energy. Most nuclear power plants operating around the world today rely primarily on uranium-235 because it is easily fissionable, whereas uranium-238 is not.
High-level radioactive waste from power plants used for energy production (e.g. SNF) contains large amounts of unused fuel, primarily comprised of unused uranium-238, unused uranium-235, plutonium, fission products and actinides. Produced in the nuclear reactor, plutonium and actinides have a very long "radioactive life" and are the main reason for keeping radioactive waste isolated and shielded for hundreds of thousands of years.
Between the 1950s and 1970s, a second class of reactors were developed to better exploit uranium reserves. The first reactor to produce electricity was EBR-I: the Experimental Breeder Reactor-I, a fast reactor that first produced electricity in the United States in 1951. These fast breeder reactors can generate more fuel than they consume, mainly using unused uranium-238 and the byproducts of nuclear reactions as fuel. When targeted by fast neutrons, the so-called radioactive "waste” can be fissioned, generating energy.
One Nuclear Technology Offering Several Solutions
Most nuclear power plants worldwide are currently operating as thermal reactors, largely due to countries halting the development of fast reactors in the past decades. Many reasons could be linked to the limited success of fast reactors, from a non-policy point of view one may consider their construction and operating procedures, technological challenges, the need for additional ad hoc facilities, the abundance of uranium resources, and the process necessary for fuel recycling (reprocessing). Some countries have adopted or are still considering using fast reactors for either electricity generation or R&D services.
A large deployment of thermal reactors worldwide may push for a reintroduction of fast reactor technology to better recycle and reuse nuclear materials, reduce the quantity of radioactive waste to be stored in geological repositories and minimize the time required for their containment and isolation. It should be noted that both options can be considered, option 1 is a responsibility towards the current status and trends of nuclear power generation, while option 2 can be considered by each country according to their needs. In this context, Jensen Hughes offers guidance and consulting services driven by technical excellence and a holistic and comprehensive technological approach to evaluate each client’s needs.
As nuclear industry experts, we conduct feasibility studies and develop strategic plans for the safe, efficient management of nuclear waste and use of nuclear materials. Our approach is focused on offering sound solutions to complex challenges, with safety and security at the forefront of each assessment.
